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Frequently Asked Questions

Here you will hopefully find some answers to common questions regarding Boxer engines.

Q. Which are the best cams to fit?

A. That's a very difficult one to answer simply. It will depend on a multitude of factors. In a standard engine, with no modifications at all, the best have got to be the 105 standard cams as fitted to the AlfaSud Green Cloverleaf. They work well, and if you do make some minor mods they will work well with these too.

If you are talking about aftermarket cams, like Piper, Kent Holbay etc, then things are definitely more complicated. The thing you will have to decide is what you want the engine to do. If you want to race on a circuit, then use race cams. If you are going to use the car on normal roads, and you know that you will encounter traffic on regular occasions, then do not use anything hotter than a fast road cam. In between those two points you have to consider a few factors. Fitting road/rally spec or rally spec cams is a waste of time anyway if you are not going to increase the compression ratio and rolling road tune the carburettors to suit, because it will be a dog to drive. Even if you are going to re-tune the carbs and up the ratio, bear in mind that it will be more difficult to drive at low RPM and in traffic. I personally wouldn't fit road/rally cams unless I was going to do sprint events or such other competition things. Cost is another issue, as fitting cams will involve a lot of money for a relatively small gain, and the gains are smaller if you don't do the compression hike and tuning. Your money may be better spent on a bigger engine, or a head 'porting' job which will also partially freshen up the engine.

Whatever, remember that a bigger engine will make a wild cam less wild, and that an injected car is a little more tolerant than carburettors of hot cams.


Q. What is the cheapest way to get a power increase?

A. Assuming that it hasn't been done already, a rolling road tuning session will give you the most horsepower for each pound spent.

Running my Sprint up on Mech Repairs rollers in Gloucester after I'd finished rebuilding the engine cost me 116 pounds. Sounds a lot? When I was on my way there, I thought the engine was great, and that all it would do is help the idle and emissions etc. They found an extra 34bhp at the top end, where the fuelling was weakening off slightly, due to more demand by the engine. In addition, the part throttle response and low end torque was a world apart. The emissions were good, and the idle steady as a rock. And the car also used less fuel. If you consider the cost, then I spent 3 pounds 42 pence for each horsepower gained. If you buy a pair of filters that give you 4 bhp more, and the filters cost 60 quid for the pair, that works out at 15 pounds per bhp gained.

If you are modifying your engine in stages, this can work out a bit more expensive. Obviously, you must try and work out when you are going to do the tuning so you are not repeating unnecessarily. For example, if you have just put on some filters and an exhaust, but are in the near future are going to modify the head and valves I would wait until the head work had been done before tuning the whole lot together.


Q. Is aftermarket injection worth it?

A. If you can spare the cash, yes, definitely. The difference in driveability is incredible, and apart from the initial price, there are no downsides, especially if you've put hot cams and things in. You get fully mapped ignition thrown it too, which makes a difference on it's own.


Q. Are all the heads interchangeable?

A. All 8v heads will fit on 8v blocks, but the heads have different inlet manifold flanges depending on the induction system used. Single carburettor engine heads are not interchangeable with dual carburettor heads, and I believe that the injected heads also have a slightly different manifold pattern. 16v heads again seem to fit the 8v block, but require sump pan changes, and the inlet and exhaust flanges are different to all other heads.


Q. The  later 1.7 carburettor engines have 40mm carburettors, can I fit them to my 1300 or 1500 twin carb?

A. They will physically fit with no problems at all, but the 40's are best left to the 1700 engines, unless your 1500 is well modified, or your 1300 is a race spec engine. They are simply too big for standard engines, you may get one bhp more at the top end by you'll lose much more than that at the bottom end, where you really need it.


Q. The cam belt change interval for these engines seems short, and they are a pain to do. Is that short a replacement period really necessary?

A. Talk to anyone who has suffered a cambelt failure, and you will get a strong answer for this. The destruction that results from a failure is expensive and will leave you stranded. You won't have any warning, either, like on an alternator belt.


Q. Every time I start the car, there is a cloud of blue smoke from the exhaust. After that it doesn't blow out smoke again and the engine sounds fine. Is my engine knackered?

A. Probably not. Because of the design of the engine, oil can run along the valve guides into the inlet port and exhaust port when you turn the engine off and the oil is nice and thin. When you start the engine, the pooled oil is burned off, and oil does not travel down the guides in any quantity. The signs of a clapped out engine is when oil smoke is being produced almost all the time, but especially when the engine is on the over-run, or under hard acceleration.


Q. My engine seems to use a hell of a lot of oil, especially compared to my Cavalier / Mondeo / Golf (delete as applicable). Is this normal?

A. Yes. Mine always have, even after complete engine rebuilds. It's another characteristic of the engine, which let's face it has lots of interesting characteristics. If it bothers you, get in the car, drive the car properly round a few country lanes for half an hour, then see if it still bothers you. If it does, then maybe the Alfa is not the car for you.....?


Q. Every time I quickly change from first to second gear, I get a crunch from the gearbox,and sometimes even from second to third. Is my gearbox on the way out?

A. No, you have a typical boxer gearbox, and thankfully you are driving it correctly. If it doesn't crunch, it's either very new, or you should be driving a Toyota Corolla. The synchros wear rapidly on second, and sometimes third on hard driven cars,  but the rest of the gearbox is bomb-proof. They can be repaired using repair kits, but a cheap way is to swap the 5th gear synchro with 2nd and 4th with 3rd. If your 5th gear synchro is worn, you deserve a medal....

A good preventative measure is to fill the gearbox with a good quality fully synthetic gear oil. It's expensive, but all the big manufacturers do it, and it makes a difference to the way the gearbox feels.


Q. Is there any way to get my car to do 0 to 60 is less than 4 seconds, and can I fit 19 inch wheels with 365 section tyres?

A. XR3I owners are down the corridor, office 3a


Q. What should I do to keep the engine reliable?

A. Obviously, keep the oil and water levels checked, and replace the cambelts at the prescribed intervals.

The majority of breakdowns can be attributed to ignition problems. Checking the condition of the spark plugs, HT leads, distributor cap and rotor arm every couple of thousand miles is heartily recommended, especially inside the distributor cap and the rotor arm contact. These can develop deposits on the electrical contacts which make the passage of the spark more difficult. Scraping them off regularly, and replacement when they start to look too bad will stave off problems. The rotor arm has a spring loaded, centrifugally operated rpm limiter. If the spring breaks, it will cut out at 2 rpm. The use of a good quality silicone based water repellent is worthwhile too, especially in the UK and north of Europe.

When checking the water and oil, look for a mayonnaise like substance inside the water and oil filler caps, this is a sign that one of your head gaskets is leaking. If you are suffering unexplained water loss, investigate it. It may be something as silly as the pressure cap on the header tank loose or weak, but by the same token it may be something more serious. Check the radiator and the block core plugs for leaks, and don't forget that the heater uses a little radiator that can burst.

Check the alternator belt for signs of it beginning to deteriorate - don't wait till it fails, do it now. If your charging light comes on every time you turn on the lights, its a sign that the alternator has seen better days.

Check that the engine is earthed properly, and that the earthing strap between the battery and the car isn't in bad condition, as it can cause starting problems.

If the low oil pressure light comes on occasionally at idle when the engine is really hot, this is ok, but if it stays on all the time at idle, you may need to look at replacing your oil pump.


Q.Alfa recommend these funny looking Golden Lodge 25HL spark plugs for the boxer, but they are expensive, I can't find a stockist and the local dealer tells me that you can use standard Champion or NGK type plus no problems. Who is right?

A. This is a very common question. First, lets start with the party line. The designer and manufacturer of the engine says use the Golden Lodge plugs. Whatever else happens, you know you can't do wrong by using them, and due to their design, they will actually last longer than normal plugs, so that tends to offset their cost. They also (at least in theory) need no re-gapping so the need to check them so often is lessened (the 16v owners out there will now be paying attention).

In practice, I have used the Champion, NGK, Nippondenso and Bosch alternatives (refer to their catalogues for the correct part number) on standard and modified engines, and never actually seen any difference at all. If the plug provides the spark at the right depth, without pysically interfering with any moving components, doesn't foul due to cold running or suffers from overheated electrodes,  the engine will run happily. That's a lot of conditions to satisfy, but you can be certain that the manufacturers have done their homework. Like I said, I never noticed any difference.

As for the longer time between checking them, well, I am one of those masochists who delves under the bonnet for pleasure, so it isn't a chore for me, and I would also consider changing the plugs a bit more often as a cheap insurance policy against breakdowns. 16v owners may find it difficult to get at their plugs, but may I suggest pushing their dead car on a rainy night is a bit more of a pain...?

The matter is a little more thorny when you modify engines. There is very little you can do away from the rolling road other than make sure you don't fit a plug that will damage the engine.

What you will have to do is determine the longest plug that can fit in without contacting the piston by performing a dry build, minus head gasket, and then putting plasticene or blutack on the end of a spark plug, installing it and turning over the engine. The plasticene will squash to the maximum length the plug can be, and you will still have the insurance of the gasket thickness in hand. You now know the longest reach plug you can physically fit. Now all you have to do is determine which is the correct plug for your engine on the rolling road, knowing the maximum length it can without causing damage to the engine.


Q. I want to fit an aftermarket filter to my car, but I have heard that I will need to re-tune my engine to suit it. Is this true?

A. Yes, it is possible. If your existing filter is restrictive, then as you are replacing it with one that has the capacity to flow more air, you may find that at high airflow situations, your mixture may be slightly lean as a result. However, not all aftermarket filters are better than the one they replace, unless the old filter is dirty. The air filter on the twin carburettor Sud and Sprint has a very large area, and as such is not that restrictive when clean. Most people go for them for looks or the louder induction roar. Whatever you do, a rolling road session will correct this.


Q. I want to fit an aftermarket exhaust to my car, but I have heard that I will need to re-tune my engine to suit it. Is this true?

A. Yes, it is possible. As in the case of the filters, If your existing exhaust is restrictive, then as you are replacing it with one that has the capacity to flow more air, and has different pulse tuning effects, you may find that at certain rpm situations, your mixture requirements may be slightly different as a result. However, not all aftermarket exhausts are better than the one they replace. A rolling road session will sort this out.


Q. You keep on and on about rolling road tuning, do you really think it is worth it?

A. Yes, and just in case you are going to ask again, YES!!! See my Q and A regarding cheapest bhp above.


Q. A lot of people say that there is no way that my Alfa has as much power as Alfa say. Are they right?

A. Unfortunately, in the majority of cases of Suds, Sprints and 33's that is true. The boxer engines were produced with compression ratios that were somewhat less than design, and some of the poor manufacturing tolerances for machining and casting made for an engine that was somewhat less than ideal. You can bet that the 105 bhp engines produced nearer 95, the 95 bhp engines nearer 85.

That they still feel bloody good is a testament to their basic good design. It also means that you can improve them, or at least bring them back to what they should be. One '95 bhp' engine that I modified produced a true 108 bhp with no aftermarket parts engine parts. All the components in the engine were standard '95 bhp' parts, including the cams and valves, modified as per the diagrams on this site. If the '95 bhp' engine was better than normal at 90 bhp, then I got an extra 18 bhp with no expensive bits, just hard work.


Q. My engine is fitted with a catalytic converter, so I am losing power compared to a non catalysed car. Should I remove it?

A. Not necessarily, and not necessarily. Having a cat fitted does not automatically mean you lose power, as some are quite free flowing designs. As for removing it, bear in mind that the legislation in force in your particular country may prohibit removal of it. In the UK, there is a cut off point, where cars built after that date must be fitted with a cat. If your car is older than this, then a 'cat replacement' pipe could be fitted, though my ecological conscience tells me to recommend fitting an after market replacement, which are better than old designs.


Q. Can I run on unleaded petrol?

A. Yes. All boxer engines have aluminium heads, which mean that valve inserts are fitted as standard. All are capable of running unleaded, though the timing may have to be retarded slightly (6 degrees from memory) to prevent pinking. On Injected cars, this is taken care of by ignition trim plugs.


Q. My engine always seems to run cold, and takes ages to get up to that temperature. I only get up to full temperature when stuck in traffic. What is wrong?

A. You probably have a stuck thermostat, which is open all the time. Replacing it will probably fix the problem. If it does not, check your water temperature sender - if your fan is operating and the gauge says 70 degrees, your sender is probably duff.


Q. The idle on my engine is rough, and I get a strong smell of petrol at the same time.

A. The float level in one or more of your carburettors may be too high, or possibly there is a leak in the idle circuit. Unless you are very confident in your skills with carbs, take it to a qualified repairer to get these points fixed. Did I mention rolling road tuning....?


Q. The choke cable on my twin carburettor car has just broken, and I am finding it difficult to get another. What should I do?

A. Absolutely nothing, in my experience. The twin carb cars I have had have all started perfectly well from cold by just giving a few dabs on the throttle as it starts, then holding it at a 1500 rpm idle for 30 seconds. On my Sprint, with the modified 108 bhp 1500 with 36IDF's, I never ever fitted a choke cable.


Q. What oil should I use for my engine?

A. It depends on the engine you have got, and how old it is.

If you have just finished an engine rebuild, whether an 8v or a 16v, and have not yet run in your engine, use Castrol GTX or equivalent for the first 500 to 700 miles. If you use too good an oil, like a fully synthetic, the engine cannot run in or bed in properly and you may get glazed bores. This will mean that your engine rings will never seal properly, losing both power and oil. Once you have run in the engine, change the oil (and don't forget the filter) for the oil recommended below.

If you have a 16v, or a just rebuilt but run in modified 8v, go for a fully synthetic, like Mobil 1 or Castrol RS. All the top brands do them, and there is little to choose.

If your engine is a rebuilt standard 8v, or a well run in modified unit (read old, high mileage) then any semi synthetic is going to be fine, like Castrol Magnatec etc.

If your engine is an old 8v, or tends to use oil rather more quickly than is normal, stick to the basic oils from the major suppliers, like Castrol GTX.


Q. Should I fit an oil cooler?

A. If you drive hard or in a hot climate regularly, I recommend it. A thermostatically operated oil cooler will keep the oil temperature down, and aid oil pressure at low revs. If you don't drive that hard that regularly, and the climate is cooler, don't worry so much. Whatever, an oil cooler will never hurt the engine, so it can be viewed as an insurance policy.


Q. Should I baffle the sump of my engine?

A. As for the previous question, if you drive hard or in a hot climate regularly, I recommend it. A baffled sump will keep the oil pressure up during hard turns especially at low revs. If you don't drive that hard that regularly, and the climate is cooler, don't worry so much. Whatever, a baffled sump will never hurt the engine, so it too can be viewed as an insurance policy.